docs: def get_unused_list_annotation_values(graph) -> Mapping[str, Set[str]]:
      """Get all of the unused values for list annotations.
  
      :param pybel.BELGraph graph: A BEL graph
      :return: A dictionary of {str annotation: set of str values that aren't used}
      """
      result = {}
      for annotation, values in graph.annotation_list.items():
          used_values = get_annotation_values(graph, annotation)
          if len(used_values) == len(values):  # all values have been used
              continue
          result[annotation] = set(values) - used_values
      return result